x402 Discovery MCP Server

An MCP server that exposes the x402 Service Discovery API as native tools for Claude, Cursor, Windsurf, and any MCP-compatible host.

x402 is an HTTP micropayment protocol: services return HTTP 402 with payment instructions; agents pay in USDC on Base and retry. No API keys, no subscriptions. This MCP server lets AI assistants find those services at runtime — and now verify their on-chain trustworthiness via ERC-8004.

Tools

Tool	Description	Cost
`x402_discover`	Quality-ranked search by capability, price, or keyword	$0.005/query
`x402_browse`	Full catalog grouped by category	Free
`x402_health`	Live health check for a specific service	Free
`x402_register`	Register your own x402 endpoint	Free
`x402_trust`	ERC-8004 on-chain identity, reputation & attestations for a wallet	Free

Quickstart

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "x402-discovery": {
      "command": "docker",
      "args": ["run", "--rm", "-i", "ghcr.io/rplryan/x402-discovery-mcp:latest"]
    }
  }
}

Cursor / Windsurf

{
  "x402-discovery": {
    "command": "docker",
    "args": ["run", "--rm", "-i", "ghcr.io/rplryan/x402-discovery-mcp:latest"]
  }
}

Run directly with Python

pip install mcp requests
python server.py

Example usage

Once installed, ask Claude:

"Find me an x402 API for web research under $0.10 per call"

Claude will call x402_discover(capability="research", max_price_usd=0.10) and return quality-ranked results with endpoint URLs, pricing, and uptime data.

"Is this wallet trustworthy? 0xDBBe14C418466Bf5BF0ED7638B4E6849B852aFfA"

Claude will call x402_trust(wallet="0xDBBe...") and return ERC-8004 identity verification, reputation score, and attestations.

Trust Layer: ERC-8004

As of v6.3.0, every service in the catalog includes on-chain trust signals from ERC-8004 — the decentralized AI agent trust standard launched January 2026.

Trust fields on every service:

{
  "name": "Tavily AI Search",
  "price_usd": 0.002,
  "health_status": "healthy",
  "erc8004_verified": true,
  "erc8004_reputation_score": 92,
  "erc8004_attestations": 14,
  "erc8004_source": "well-known"
}

The x402_trust tool:

x402_trust(wallet="0xDBBe14C418466Bf5BF0ED7638B4E6849B852aFfA")

Returns on-chain identity URI, reputation score, attestation count, and whether the service hosts a /.well-known/erc8004.json declaration.

Why it matters: The x402 Bazaar has 33M+ transactions/month but avg service fidelity is ~38/100. ERC-8004 trust signals let agents filter for verified, reputable services — not just the cheapest ones.

Discovery API

This MCP server wraps the public x402 Service Discovery API:

GET /catalog — full index, free, ungated
GET /discover?q=research — quality search ($0.005/query)
GET /trust/{wallet} — ERC-8004 trust lookup for any wallet address
GET /.well-known/x402-discovery — machine-readable catalog (RFC 5785)
POST /register — self-service provider registration

Interactive Demo →

License

MIT

x402 Service Discovery